Hospitals and other medical centers are scrambling for ventilators in the U. S. and across the globe to help save lives during the Coronavirus pandemic.
EMS providers, contract manufacturers, and PCB fabricators are engaging with medical equipment customers to put into action vast numbers of new PCB orders specifically for the manufacture of thousands of new conventional and portable ventilators.
Medical ventilator OEMs must keep in mind traditional, well-proven PCB assembly and manufacturing technologies are critical to assure their products demonstrate the highest possible quality and reliability. Proper and correct thermal profiling is among those top PCB assembly and manufacturing technologies.
An incorrect thermal profile can lead to poor quality and reliability. For example, excessive heat can lead to possible de-lamination issues on the PCBs so that board reliability is compromised, Fig. 1. Tombstoning is another issue that arises with excessive heat, Fig. 2. Here, one side of the component is pulled causing the other end to stand up.
Read our recent SMT007 Magazine article detailing the proper way a thermal profile must be created and implemented. In the meantime, here are some tips and hints to give you a better understanding.
- A thermal profile is basically a recipe for preparing an SMT component-populated PCB for the IR reflow oven.
- Three steps are involved: stencil printing, pick and place system automatically places components on the board, and the PCB goes through either an IR reflow oven or through vapor phase.
- A solder sample board is used and is designed based on the solder paste specifications of a particular manufacturer.
- The thermal profile must factor in the number of copper layers on the board, especially power and ground.
- For PCB microelectronics assembly, there are thermal profile requirements associated with a particular die being used on the PCB.
- Also, during PCB microelectronics assembly, a die’s moisture sensitivity level must be accounted for to assure it is optimally preserved without moisture seeping into the package.
These and many other factors need to be included while a thermal profile is developed. For instance, it’s important to keep in mind is that today’s PCBs are populated with highly advanced device packaging. Consequently, the process engineer is highly challenged when creating the correct thermal profile, not only for the component side, but especially for the solder side.
Also, PCBs are becoming more dense and smaller to comply with portable applications such as portable ventilators. Plus, in the industry today, there are a vast number of different size boards, each requiring a unique thermal profile. Therefore, it is very important that the EMS provider to develop a one-of-a-kind profile for each board.